Glans
The glans penis (or simply glans) is the sensitive bulbous structure at the distal end of the penis. It is also commonly referred to as the 'head of the penis.' Slang terms include "helmet," "nob" (or "knob"), and "bell end," and all refer to its distinctive shape. The glans penis is anatomically homologous to the clitoral glans of the female. When the penis is flaccid it is sometimes wholly or partially covered by the foreskin, except in men who have been fully circumcised. The foreskin serves to protect this delicate mucous membrane covered structure. Anatomical details The glans penis is the expanded cap of the corpus spongiosum. It is moulded on the rounded ends of the Corpora cavernosa penis, extending farther on their upper than on their lower surfaces. At the summit of the glans is the slit-like vertical external urethral orifice. The circumference of the base of the glans forms a rounded projecting border, the corona glandis, overhanging a deep retroglandular sulcus (the coronal sulcus), behind which is the neck of the penis. The proportional size of the glans penis can vary greatly. On some penises it is much wider in circumference than the shaft, giving the penis a mushroom-like appearance, and on others it is narrower and more akin to a probe in shape. It has been suggested that the unique and unusual shape of the glans in humans has evolved to serve the function of "scooping" any remnant semen deposited by other rival males out of the deeper part of the vagina of a female who may have recently copulated, and thereby decreasing the chance of the rival male from impregnating the female. Other theorists suggest that its distinctive shape evolved to heighten the sexual pleasure experienced by the female during vaginal intercourse. In this theory, the glans increases friction and tension at the mouth of the vagina by its additional girth and the dilating properties of its probe-like shape. This maximises indirect stimulation of the clitoris by the repetitive thrusting movements of the penis inside the vagina during intercourse. The foreskin maintains the mucosa in a moist environment. In males who have been circumcised, but have not undergone restoration, the glans is permanently exposed and dry. Szabo and Short found that the glans of the circumcised penis does not develop a thicker keratinization layer. Studies have suggested that the glans is equally sensitive in circumcised and uncircumcised males. (excerpt accessible here) Halata & Munger (1986) report that the density of genital corpuscles is greatest in the corona glandis, while Yang & Bradley (1998) report that their study "showed no areas in the glans to be more densely innervated than others." Halata & Spathe (1997) reported that "the glans penis contains a predominance of free nerve endings, numerous genital end bulbs and rarely Pacinian and Ruffinian corpuscles. Merkel nerve endings and Meissner's corpuscles are not present." Yang & Bradley argue that "The distinct pattern of innervation of the glans emphasizes the role of the glans as a sensory structure". Additional images Image:Anteriorglanspenis.jpg|An anterior view of a male's flaccid penis with the covering foreskin fully pulled back and the underneath glans head fully exposed. See also *Clitoris *Corpus cavernosum penis *Foreskin *Frenulum of prepuce of penis *Hirsuties papillaris genitalis References External links * - "The Male Perineum and the Penis: The Corpus Spongiosum and Corpora Cavernosa" * - "The Male Pelvis: The Urethra" Category:Male reproductive system Category:Penis